In general, an optical connector comprises a ferrule which is bonded to an end portion of an optical fiber. Normally, in order to achieve optical connection using two optical connectors of this type, ferrules of the optical connectors are brought into contact with each other in an axial direction thereof. In this case, in order to ensure the stable contact between the ferrules, use is made of an optical connector adapter comprising a tubular member generally called a split sleeve which has an axial slit extending along the entire length thereof. Specifically, the ferrules are inserted into the split sleeve from its axial ends, respectively, so that the ferrules are brought into contact with each other in the sleeve. As a result, optical connection between optical fibers is obtained. Hereinafter, such a split sleeve will be simply referred to as a “sleeve”.
This type of optical connector adapter is disclosed in, for example, JP-A-2003-270489 (Patent Document 1) or JP-A-2001-33658 (Patent Document 2), wherein one axial part of a sleeve is held by a shell-side hollow cylindrical portion integrally formed in a shell while the other axial part of the sleeve is held by a holder-side hollow cylindrical portion of a sleeve holder inserted in the shell. The sleeve holder is prevented from being detached from the shell by the use of holes formed through the shell.